My experience is strictly from playing the piano, but despite the difference in the specific motion required, the approach to building speed is the same.
The short answer to your question is, "Don't do it".
It's tempting to use the metronome to push yourself faster, but this strategy doesn't work largely for the same reason that this strategy doesn't work while lifting weights. If your muscles can't handle it, they can't handle it. Pushing yourself at the limit of what your muscles can handle is a recipe for introducing bad habits into your technique.
I would advise you to not push yourself like that. I'm not saying to never explore your limits--if you don't push yourself with the metronome every once in a while, you'll never know where that limit is. I'm arguing that your normal tremolo practice should happen at a challenging tempo a few notches down from your absolute limit. You will build up speed over time, even if you're not playing at the bleeding edge of your ability.
I personally hate practicing like this, because I am impatient and this method both obscures and slows the rate of improvement. However, because when I was younger I pushed my tremolo tempo without regard to technique (because I really wanted to play this.....I can hit all the notes, but fall short of making music), I picked up the bad habit of retaining tension in my forearms. After years of practice, I still haven't kicked that habit. Be safe. Do it right the first time. And good luck!
